Amino acid compositions and use thereof in treating renal dysfunction

ABSTRACT

A method for the use of at least one amino acid selected from the group consisting of glycine, alanine and serine, or the physiologically acceptable salts thereof (component (a)), in the preparation of a medicament or nutritional formulation for the prophylaxis and/or therapy of renal dysfunction induced by cyclosporins or ascomycins.

The present invention relates to the use of specific amino acids in the preparation of a medicament or nutritional formulation which may be therapeutically administered to patients to prophylactically and/or therapeutically treat renal dysfunction induced by substances belonging to the classes of cyclosporins and/or ascomycins.

Cyclosporins comprise a class of structurally distinct, cyclic, polyN-methylated undecapeptides, generally possessing immunosuppressive, anti-inflammatory, anti-viral and/or anti-parasitic activity, each to a greater or lesser degree. The first of the cyclosporins to be identified was the fungal metabolite Cyclosporin A, or Ciclosporin, and its structure is given in The Merck Index, 11th Edition; Merck & Co., Inc.; Rahway, N.J., USA (1989) under listing 2759. Later cyclosporins to be identified are cyclosporins B, C, D and G which are also listed in The Merck Index under listing 2759. A large number of synthetic analogues are also known and representative examples are disclosed in EP 296 123, EP 484 281, and GB 2222770. Cyclosporin A and its structurally similar analogues and derivatives as well as metabolites thereof are generally referred to as "cyclosporins" for the purposes of this specification.

Ascomycins, of which FK-506 is the best known, are another class of generally immunosuppressive substances, also referred to as macrolide immunosuppressants. FK-506 is a macrolide immunosuppressant that is produced by Streptomyces tsukubaensis No. 9993. The structure of FK-506 is given in the appendix to The Merck Index, supra, as item A5. A large number of related compounds which retain the basic structure and immunological properties of FK-506 are also known. These compounds are described in various publications, for example EP 184162, EP 315973, EP 323042, EP 423714, EP 427680, EP 465426, EP 474126, WO 91/13889, WO 91/19495, EP 484935, EP 532088, EP 532089, WO 93/5059 and the like. Ascomycin, FK-506 and their structurally similar analogues and derivatives as well as metabolites thereof are termed collectively "ascomycins" in this specification.

Due to their extremely useful pharmaceutical properties, cyclosporins (Cyclosporins A and G in particular) and ascomycins (e.g., FK-506) have wide application in, for example the prevention of transplant rejection, in the treatment of auto-immune diseases such as rheumatoid arthritis and psoriasis, and also in the treatment of multi-drug-resistance. Cyclosporins and ascomycins also have certain side effects, the most notable being renal dysfunction, in particular nephrotoxicity, especially at higher doses. Nephrotoxicity is characterized by diminished renal blood flow and glomerular filtration with corresponding elevations in serum creatinine, alkaline phosphatase and urea as well as proximal cell swelling and necrosis and infiltration of macrophages. In some studies, hypoxia has been shown to damage proximal tubules rather selectively, and a decrease in blood flow could lead to hypoxia. Evidence has been presented implicating intracellular calcium in this pathology, and calcium channel blockers are effective in minimizing injury. However, Ca⁺⁺ channel blockers cannot be given without impunity. Accordingly, there is currently no known useful therapy for this important side effect on the kidney.

It has now surprisingly been found that, inter alia, glycine is suitable for prophylactic and/or therapeutic treatment of renal dysfunction induced by cyclosporins or ascomycins.

In accordance with the invention it has more particularly been found that dietary glycine inhibits and/or ameliorates one of the major side effects of chronic cyclosporin A administration-nephrotoxicity. Glycine prevents the decrease in glomerular filtration rate. Glycine also prevents the elevation in serum creatinine and urea, and tends to minimize the elevation in alkaline phosphatase due to cyclosporin A. The swelling and necrosis of proximal tubules and macrophage infiltration are also all prevented by dietary glycine. Thus, it is clear that glycine has a major protective action on nephrotoxicity due to cyclosporin A.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bar graph depicting the mean serum creatinine levels (mg/dl) observed in four treatment groups of rats following the administration of a daily 200 g powdered diet of, respectively, control (20% casein), glycine (15% casein+5% glycine) cyclosporin [CsA] (25 mg/kg cyclosporin soluted as 2.5 mg/ml in olive oil) or cyclosporin+glycine for four weeks [a=p<0.05 compared to control; b=p<0.05 compared to CsA].

FIG. 2 is a bar graph depicting the mean glomerular filtration rate observed in each of the treatment groups following four weeks of treatment [a=p<0.05 compared to control; b=9<0.05 compared to CsA].

FIG. 3A is a bar graph depicting the mean number of dilated proximal tubules per slide observed in each of the treatment groups under low power (100×) at necropsy following four weeks of treatment [*=p<0.05 compared to control].

FIG. 3B is a bar graph depicting the mean number of necrotic cells in each of the treatment groups counted on five different tubules per slide under high power (400×) at necropsy following four weeks of treatment [*p=<0.05 compared to control].

FIG. 4 is a bar graph depicting mean number of macrophages observed proximate to 5 different tubules per slide under high power (400×) in each of the treatment groups at necropsy following 4 weeks of treatment [*=p<0.05 compared to control].

FIG. 5 is a bar graph depicting the percentage of neutrophils found as a function of the total number of white blood cells in the control and CsA treatment groups [*=p<05.05 compared to control].

In view of the above-mentioned effects, there are provided pharmaceutical compositions, formulations and diets comprising glycine as well as methods of using glycine. For use in the compositions, formulations, diets and methods of the invention, glycine is conveniently employed in free amino acid form, in the form of glycine precursors, in particular alanine or serine, likewise in free amino acid form, in physiologically acceptable salt form of said amino acids, or in form of mixtures of said amino acids and/or physiologically acceptable salts thereof. Glycine is preferably used in free amino acid form, in physiologically acceptable salt form or in the form of a mixture of glycine in free amino acid form with glycine in physiologically acceptable salt form; most preferably glycine is in free amino acid form. Glycine may also be used in the form of dipeptides according to the invention.

The term "amino acid of the invention" as used hereinafter is meant to refer to glycine, alanine and/or serine, in free amino acid form and/or physiologically acceptable salt form.

This invention therefore provides the use of at least one amino acid selected from the group consisting of glycine, alanine and serine, or physiologically acceptable salts thereof, in the preparation of a medicament or nutritional formulation for the prophylaxis and/or therapy of renal dysfunction induced by cyclosporins or ascomycins.

The invention further provides a method for the prophylactic and/or therapeutic treatment of renal dysfunction induced by cyclosporins or ascomycins comprising administering to a human being prior to, simultaneous with, or subsequent to the treatment with a cyclosporin or ascomycin at least one amino acid selected from the group consisting of glycine, alanine, serine and physiologically acceptable salts of glycine, alanine and serine, in an amount effective to inhibit and/or ameliorate the renal dysfunction.

Still further the invention provides a medicament or nutritional formulation comprising at least one amino acid selected from the group consisting of glycine, alanine and serine, or physiologically acceptable salts thereof for the prophylaxis and/or therapy of renal dysfunction induced by cyclosporins or ascomycins.

The invention also provides a medicament or nutritional formulation comprising a therapeutically effective amount of a cyclosporin or ascomycin in combination with at least one amino acid selected from the group consisting of glycine, alanine and serine, or the physiologically acceptable salts thereof, in an amount effective to inhibit and/or ameliorate the renal dysfunction induced by the cyclosporin or ascomycin.

The amino acids of the invention are particularly useful in the prophylactic and/or therapeutic treatment of the renal dysfunction nephrotoxicity.

The amino acid of the invention is further particularly useful for the therapy and/or prophylaxis of renal dysfunction induced by the cyclosporins cyclosporin A (Ciclosporin) and PSC 833 ([3'-desoxy-3'-oxo-MeBmt]¹ [Val]² -Ciclosporin, e.g. as described in EP 296 122), particularly by cyclosporin A.

The amino acid of the invention is also particularly useful for the therapy and/or prophylaxis of renal dysfunction induced by the ascomycins FK-506 and ASM (33-epichloro-33-desoxy-ascomycin, e.g. as described in Ex. 66a of EP 427 680), particulary by FK-506.

Furthermore, the amino acid of the invention is particularly useful for the prophylaxis and/or therapy of renal dysfunction induced by immunosuppressive cyclosporins or ascomycins.

The nutritional formulation or medicament may be administered to the patient enterally or parenterally. The enteral administration route is preferred, particularly for subsequent or prophylactic treatment; particularly contemplated enteral administration routes are oral administration, nasal administration and/or tube feeding. The medicament or formulation is conveniently administered in the form of an aqueous liquid. The medicament or formulation in a form suitable for enteral application is accordingly preferably aqueous or in powder form, whereby the powder is conveniently added to water prior to use. For use in tube feeding, the amount of water to be added will depend, inter alia, on the patient's fluid requirements and condition. It will be appreciated that, for acute treatment, the parenteral application route is preferred.

The medicament or formulation may be so formulated as to deliver to the patient from 1 to 80 g, preferably 10 to 60 g, particularly preferred 15 to 30 g of the amino acid of the invention per 24 hours. The amount of medicament or formulation to be administered depends to a large extent on the patients' specific requirements. Such daily amounts of amino acid of the invention are suitable for treatment of the desired effects as well as for prophylactic/pretreatment. In the case that the medicament or formulation comprises a single amino acid of the invention (in the L-configuration), it may be administered to the patient in an amount such-that the concentration of that amino acid in the patients' plasma is elevated to between 0.5 and 2.0 mM, preferably from 1.0 to 2.0 mM. Whilst concentrations higher than this are anticipated, it is expected that significant clinical effects will be obtained if the concentration of the acid is increased, as a consequence of administration of the formulation or medicament, so that it lies in the range of from 1.2 to 1.5 mM. In traumatic, hypercatabolic patients it may even be beneficial to raise the plasma glycine, serine or alanine levels to about 0.2 to 0.3 mM which corresponds to plasma glycine levels of healthy individuals.

The most preferred amino acid of the invention for incorporation into the medicament or formulation for use according to the invention is glycine or a physiologically acceptable salt thereof.

Generally, it is indicated to use an amino acid of the invention in combination with one or more of the following components:

(i) omega-3 polyunsaturated fatty acids (PUFAs) where desired in admixture with omega-6 PUFAs;

(ii) L-arginine or other physiologically acceptable compound associated with the synthesis of polyamines, or mixtures thereof; and

(iii) a nucleobase source.

Whereby the use of a medicament or nutritional formulation comprising an amino acid of the invention in combination with arginine or other physiologically acceptable compound associated with the synthesis of polyamines such as ornithine is preferred. Use of a medicament or nutritional formulation comprising an amino acid of the invention, arginine or ornithine and omega-3 polyunsaturated fatty acids (PUFAs) is also preferred.

Said nutritional formulations are hereinafter designated "diets of the inventions".

Nucleobase sources suitable for use in combination with the amino acids of the invention comprise or consist of natural nucleobases, nucleosides, nucleotides, RNA, DNA, equivalents thereof and/of mixtures comprising one or more of these compounds.

Natural nucleobases include the purines adenine and guanine as well as the pyrimidines cytosine, thymine and uracil. Where the nucleobase source is in the form of free nucleobases, it is preferably uracil.

Natural nucleosides include the ribose nucleosides adenosine, guanosine, uridine and cytidine and the deoxyribose nucleosides deoxyadenosine, deoxyguanosine, deoxythymidine and deoxycytidine.

Natural nucleotides include phosphate esters of natural nucleosides, such as the monophosphates adenylate (AMP), guanylate (GMP), uridylate (UMP), cytidylate (CMP), deoxythymidiylate (dTMP), deoxycytidylate (dCMP), and diphosphates and triphosphates of natural nucleosides such as ADP and ATP.

A purified nucleobase source, such as yeast is preferred. However, other sources such as meat and the like may be used. Preferably the nucleobase source is RNA.

Accordingly, the invention provides medicaments or nutritional formulations comprising effective amounts of:

(a) an amino acid of the invention (component (a))

in association with one or more components selected from

(b) omega-3 PUFAs where desired in admixture with omega-6 PUFAs (component (b));

(c) L-arginine or other physiologically acceptable compound associated with the synthesis of polyamines, or mixtures thereof (component (c)); and

(d) a nucleobase source (component (d)).

The dosage should be such that the medicaments or nutritional formulations are effective for the prevention and/or treatment of nephrotoxicity induced by macrolide immunosuppressive drugs.

One unit dose of such a medicament or nutritional formulation preferably comprises 1.5 to 80 parts by weight of component (a) in association with the following amounts of one or more components selected from (b) to (d): 0.1 to 20 parts by weight of component (b), 3 to 40 parts by weight of component (c) and 0.1 to 4.0 parts by weight of component (d). Particularly preferred one unit dose comprises 1.5 to 80 parts by weight of component (a) in association with the following amounts of one or more components selected from (b) to (d): 2 to 5 parts by weight of component (b), 7.5 to 20 parts by weight of component (c) and 1.7 to 2.0 parts by weight of component (d).

The amount of components (a) to (d) administered daily will conveniently correspond to 1.5 to 80 g for component (a), 0.1 to 20 g, preferably 2 to 5 g, for component (b), 3 to 40 g, preferably 7.5 to 20 g, for component (c) and 0.1 to 4.0 g, preferably 1.7 to 2.0 g, for component (d).

With respect to component (d) the above dosage is indicated for RNA, DNA, nucleosides or nucleotides. For nucleobases one weight unit of nucleobases is regarded to be equivalent to 2.5 to 3.0 weight units of RNA, DNA, nucleosides or nucleotides.

Where medicaments or nutritional formulations comprising an amino acid of the invention in combination with one or more of the above-mentioned components (b), (c) and (d) are used, such medicaments or nutritional formulations will conveniently comprise in one unit dose

(a) 1.5 to 80 parts by weight of one or more amino acids selected from the group consisting of glycine, alanine and serine, in free form or physiologically acceptable salt form, or mixtures thereof,

in combination with one or more compounds selected from the group consisting of

(b) 2 to 5 parts by weight omega-3 polyunsaturated fatty acids;

(c) 7.5 to 20 parts by weight L-arginine or L-ornithine, or mixtures thereof; and

(d) 1.7 to 2.0 parts by weight RNA.

Preferred medicaments or nutritional formulations comprise in one unit dose:

(a) from 1.5 to 80 parts by weight of an amino acid selected from the group consisting of glycine, alanine and serine, in free form or physiologically acceptable salt form, or mixtures thereof, in association with

(c) 3 to 40 parts by weight, preferably 7.5 to 20 parts by weight, of arginine or an equivalent amount of one or more other physiologically acceptable compound associated with the synthesis of polyamines, or an equivalent amount of a mixture of arginine with such compound.

More preferably the medicaments or nutritional formulations of the invention comprise component (a) in combination with component (c) at a weight ratio of 1:2 to 4:1, particularly preferred at a weight ratio of 1:1 to 2:1.

Further preferred medicaments or nutritional formulations comprise in one unit dose:

(a) from 1.5 to 80 parts by weight of an amino acid selected from the group consisting of glycine, alanine and serine, in free form or physiologically acceptable salt form, or mixtures thereof, in association with

(b) 0.1 to 20 parts by weight, preferably 2 to 5 parts by weight, of omega-3 PUFAs; and

(c) 3 to 40 parts by weight, preferably 7.5 to 20 parts by weight, of arginine or an equivalent amount of one or more other physiologically acceptable compound associated with the synthesis of polyamines, or an equivalent amount of a mixture of arginine with such compound.

Omega-3 PUFAs are conveniently protected against peroxidation during storage of the formulation.

Physiologically acceptable ways of protecting omega-3 PUFAs against peroxidation during storage are known in the art. They include physiologically acceptable micro-encapsulation of omega-3 PUFAs and the use of physiologically acceptable antioxidants in amounts sufficient to protect the fatty acids.

A typical example suitable for use as physiologically acceptable micro-encapsulation agents is starch. The micro-encapsulation can be effected in a manner known per se. The micro-encapsules may be coated in a manner known per se, by physiologically acceptable coating agents such as Gum Arabic.

Typical examples of antioxidants suitable for protecting fatty acids against peroxidation include antioxidant vitamins such as Vitamin C, Vitamin E or mixtures thereof.

The amount of antioxidant added should be sufficient to prevent peroxidation of the omega-3 PUFAs. Such amounts can be easily calculated. In general, for convenience, any antioxydants employed to prevent peroxidation, will be employed in excess. It will be appreciated that the presence of any other agent administered in association with the omega-3 PUFAs may require adjustment of the amount of antioxidant to be employed.

The omega-3 PUFAs may be employed in a form suitable for the physiological supply of omega-3 PUFAs, e.g. in free acid form, in triglyceride form, or in the form of physiologically acceptable natural sources of omega-3 PUFAs. Such natural sources include linseed oil and fish oils such as menhaden oil, salmon oil, mackerel oil, tuna oil, cod-liver oil and anchovy oil. Said natural sources, in particular, the fish oils, comprise substantial amounts of omega-3 fatty acids. Where the omega-3 PUFAs are employed in triglyceride form, said triglycerides may comprise esters with other physiologically acceptable fatty acids. Preferred omega-3 PUFAs include eicosapentaenoic acid EPA) and docosahexaenoic acid (DHA), in free acid form, in triglyceride form or in form of natural sources having a high EPA and/or DHA content.

When the amino acids of the invention are administered in the form of a medicament such a medicament will comprise from 1 to 99 g of the amino acid of the invention per 100 g.

In general, favourable effects are obtained when administering the diets of the invention in the form of a formula diet, which may, depending on the circumstances be a complete formula diet (i.e. a diet supplying essentially ail required energy, amino acids, vitamins, minerals and trace elements) or a diet supplement. The diet will conveniently be take n in aqueous liquid form. A formula diet accordingly may comprise a source of carbohydrates, lipids fat (fat source) and protein (nitrogen source), and at least one amino acid selected from the group consisting of glycine, L-alanine and L-serine, or physiologically acceptable salts thereof, characterized in that the acid or salt is present in the formula diet in an amount of about 0.5 to 10 g per such. The formula diet will preferably further comprise other nutritionally advantageous components such as vitamins, minerals, trace elements, fibers (preferably soluble fibers). The amounts of carbohydrates will in the range of 0-60% by weight, the amount of fat in the range of 0-30% by weight and the amount of protein in the range of 0-45% by weight.

Examples of suitable nitro-en sources include nutritionally acceptable proteins such as soy bean or w hey derived proteins, caseinates, and/or protein hydrolysates. Suitable carbohydrate sources include sugars such as maltodextrins. Examples of suitable fat sources include triglycerides, as well as di- and monoglycerides.

Examples of vitamins suitable for incorporation into the medicament or formulation of the invention include Vitamin E, Vitamin A, Vitamin D, Vitamin K, folic acid, thiamin, riboflavin, Vitamin B₁, B₂, B₆ and B₁₂, niacin, biotin and panthogenic acid in nutritionally acceptable form.

Examples of mineral elements and trace elements suitable for incorporation into the medicament or formulation include sodium, potassium, calcium, phosphorous, magnesium, manganese, copper, zinc, iron, selenium, chromium, and molybdenum in nutritionally acceptable form.

In particular, the medicament or formulation will preferably comprise beta-carotene (Vitamin A), Vitamin E, Vitamin C, thiamine, Vitamin B₁₂, choline, selenium and zinc in nutritionally acceptable form.

The term "soluble fiber" as used herein refers to fibers which are able to undergo substantial fermentation in the colon ultimately to produce short chain fatty acids.

Examples of suitable soluble fibers include pectin, guar gum, locust bean gum, xanthan gum which may optionally be hydrolysed. For adults the total amount of soluble fibre per day will conveniently lie in the range of from 3 to 30 g.

It will be appreciated that omega-3 PUFAs may be administered in higher amounts than those indicated hereinabove, and that such higher amounts will in general not impair the desired effect or provoke undesired side effects.

Compounds particularly suitable for use as component (c) in the formulation of the invention include L-arginine and L-ornithine, most preferably L-arginine. Component (c) may be employed in free form, physiologically acceptable salt form, e.g. in the form of a salt with phosphoric acid, citric acid, tartaric acid, fumaric acid, adipic acid or lactic acid, or in small peptide form. Preferably L-arginine in free form is employed.

The term small peptides as used herein refers to peptides having from 2 to 6, preferably from 2 to 4 amino acids.

As already indicated, omega-3 PUFAs will conveniently be administered in the form of fish oils, protected or not against peroxidation. Such fish oils also comprises omega-6 PUFAs.

Omega-6 PUFAs have also a favourable effect on the immune response and on the resistance to infection upon surgery. Accordingly, diets of the invention will conveniently further comprise omega-6 PUFAs.

For the purpose of the invention the omega-6 PUFAs may be in free acid form or in a form suitable for the physiological supply of omega-6 PUFAs, e.g. in triglyceride form. Examples of omega-6 PUFAs particularly appropriate for use according to the invention, include linoleic acid and arachidonic acid, linoleic acid being, most preferred. Examples of suitable omega-6 PUFA sources are known in the art. They include fish oils and vegetable oils. Examples of omega-6 PUFA sources having a high linoleic acid content such as safflower oil, sunflower oil, soya oil, cotton oil and corn oil.

Administration of a daily amount of omega-6 PUFAs in the range of from 1.5 to 5.0 g will in general suffice to attain a favourable effect. One unit dose of the medicaments or nutritional formulation defined above may accordingly further contain 1.5 to 5 parts by weight of omega-6 PUFAs.

In addition to components (b), (c) and (d), and omega-6 PUFAs further components may be added to the diets of the invention and may have a beneficial effect on the activity of the amino acid of the invention. An example of such beneficial components are omega-9 PUFAs. A preferred natural source for such fatty acid mixtures are fish oils. For taste and other reasons, the fish oils will, in oral application forms, preferably be used in encapsulated form.

Where the formula diet of the invention is intended for use as a nutritional supplement, the amount of energy supplied by it should not be too excessive, in order not to unnecessarily suppress the patients appetite. The supplement should conveniently comprise energy sources in an amount supplying from 150 to 1000 Kcal/day, preferably 250 to 500 Kcal/day. The contribution of the nitrogen source, carbohydrate source and lipid source to the total daily caloric may vary within wide ranges. For use as a supplement, the administration may be in powder or liquid form.

The treatment period will coincide with the treatment with the immunosuppressive drug.

The supplement will conveniently be administered in the form of unit doses suitable for administration of the supplement 1 to 4 times per day. Where the diets of the invention comprise energy sources, it is appropriate not to supply more than 1000 Kcal/day. Apart from this limitation with respect to the energy supply, diet supplements of the invention for preventing and/or treating nephrotoxicity induced by macrolide immunosuppressive drugs can and will conveniently be supplied in the form of formula diets as described above.

Typical pharmacologically acceptable formulation forms for oral administration will further comprise pharmacologically acceptable diluents, carriers, vitamins, spices, pigments and/or other adjuvants well known to the skilled person to be suitable for incorporation into such formulation and optionally a macrolide immunosuppressive drug.

The diets and formulations of the invention may be obtained in a manner known per se, e.g. by admixing the ingredients.

The invention is further illustrated by the following Examples which are not intended in any way to limit the scope of the claimed invention.

EXAMPLE 1

Animal and Diets

Male Sprague--Dawley rats (Sasco) weighing approximately 200 g were fed a synthetic powdered diet containing 5% glycine and 15% casein (glycine) or 20% casein (control) for 3 days prior to initiation of cyclosporin A treatment. Components of the powdered diet are shown in Table 1. All animals were given humane care in compliance with institutional guidelines. After the prefeeding period, cyclosporin A (25 mg/kg soluted as 2.5 mg/ml in olive oil) or vehicle was given daily by oral gavage for approximately 4 weeks. Four groups of 6-8 rats each (control, glycine, cyclosporin+control, cyclosporin+glycine) were studied. Animals weight and diet consumption was measured daily.

                  TABLE 1                                                          ______________________________________                                         Composition of Control and Glycine Diets %                                     Component         Control Glycine                                              ______________________________________                                         Casein            20.0    15.0                                                 Glycine           0.0     5.0                                                  Sucrose           50.0    50.0                                                 Corn oil          5.0     5.0                                                  Cellulose         5.0     5.0                                                  Mineral mix       3.5     3.5                                                  Vitamin mix       1.0     1.0                                                  DL-Methionine     0.3     0.3                                                  Choline bitartrate                                                                               0.2     0.2                                                  Corn starch       15.0    15.0                                                 ______________________________________                                    

Glomerular Filtration Rate and Clinical Chemistry

Animals were placed in metabolic cages 48-72 hours prior to sacrifice, 24 hour urine samples were collected and 0.5 ml of blood was drawn from the tail vein for blood creatinine measurements. On the day of sacrifice, another 1 ml of blood was drawn from the vena cava and replaced with an equal volume of Ringers lactate-solution. Serum urea (Coulombe, J. J. and L. Favreau. 1963. A new simple semimicro method for colorimetric determination of urea. Clin. Chem. 9:102-108); and creatinine (Heinegard, D. and G. Tiderstrom. 1973. Determination of serum creatinine by a direct colorimetric method. Clin. Chim. Acta. 43:305-310); as well as urine creatinine were measured using, Sigma kits while serum alkaline phosphatase was measured enzymatically (blood samples were collected after approx. 4 weeks of cyclosporin A treatment). Glomerular filtration rate was calculated from the ratio of creatinine in the urine/blood (Laiken, N. D. and D. D. Fanestil. 1985. Filtration and Blood Flow. In Physiological basis of medical practice. J. B. West, editor. Williams & Wilkins, Baltimore/London. 461-471), urine samples were collected after approx. 4 weeks of cyclosporin A treatment.

On the day of sacrifice animals were anesthetized with pentobarbitol (50 mg/1 g), the abdomen was opened and the aorta was canulated with a 24 French i.v. canula with the lip placed near the renal arterial branches, The aorta was clamped above and ligated beneath the renal branches and the left kidney was rinsed with 5 ml normal saline and perfusion--fixed with 4% paraformaldehyde solution in phosphate buffered saline. The kidney was removed, cut in 0.5 thick slices and placed in 10% formaline. Hemtoxyllin--eosin sections were performed and analyzed microscopically. Dilated tubules were counted in 5 different low power fields (100×), necrotic cells and infiltrating macrophages were counted in 5 different tubules at high power magnification (400×) and averages±SEM calculated.

Quantitation of Neutrophils

Blood smears were prepared from vena cava samples on the day of sacrifice and stained with Wright Giemsa stain. Differential white blood cell counts for 200 while blood cells were performed at high power magnification (400×) and percentages calculated.

Statistics

For all statistics, one-way ANOVA and the Bonferonni post-hoc test was used. p<0.05 was selected prior to the study to indicate significance.

RESULTS

Clinical Chemistry and Glomerular Filtration Rate

It is known that cyclosporin A elevates serum urea. Indeed, urea was increased over 70% in this study (Table 2). While glycine tended to minimize this increase, the effect was not statistically significant. Cyclosporin A also increased alkaline phosphatase (Table 2), and glycine tended to prevent the increase. Serum creatinine ranged from 0.4-0.6 mg/dl in the control and glycine treated groups (FIG. 1) but was doubled significantly by cyclosporin A. This increase was prevented totally by the glycine diet. Values are means±S.E.M. (P<0.01 by ANOVA; n=5-6 in each group). a,p<0.05 compared to control; b,p<0.05 compared to the cyclosporin A group.

It is also known that cyclosporin A diminishes glomerular filtration rate. In this study, values in the cyclosporin A group were about 30% of those of control or glycine alone groups (FIG. 2). This decrease in glomerular filtration rate was also totally prevented by glycine in the diet. Values are means±S.E.M. (P<0.01 by ANOVA; n=5-6 in each group). a,p<0.05 compared to control; b,p<0.05 compared to the cyclosporin A group. Significant chances in urine volume were also noted (control, 9,1±1.6 ml/24 h; glycine, 6.7±0.8; cyclosporin A 14.4±2.3; glycine+cyclosporin A, 1 1.8±2.1).

                  TABLE 2                                                          ______________________________________                                         Effects of Cyclosporin A and a Glycine Diet                                    on Serum Urea and Alkaline Phosphotase Levels                                                  Urea       Alkaline Phosphotase                                                (Mg/dl)    (UL)                                                ______________________________________                                         Control         21.8 ± 1.8                                                                             46.5 ± 4.4                                       Glycine         20.6 ± 2.4                                                                             33.1 ± 5.6                                       Cyclosporin A   34.9 ± 3.7.sup.a                                                                       65.9 ± 12.6                                      Cyclosporin A + glycine                                                                        31.2 ± 0.6.sup.a                                                                       47.7 ± 8.8                                       ______________________________________                                    

Values are mean±S.E.M.; a, p<0.05 compared to controls by ANOVA and Student-Newman-Keuls test (n=5-6 in each group)

Histology and White Blood Cells

It is clear that cyclosporin A causes proximal tubular swelling and necrosis with associated white blood cell infiltration as-has been reported previously. These effects were totally prevented by the glycine-containing diet. On average, proximate cell swelling and necrosis as well as infiltrating macrophages were elevated significantly by cyclosporin A (FIGS. 3, 4). Dilated proximal tubules (panel A of FIG. 3) were counted in three different low power fields per slide (magnification 100×) and average±S.E.M. calculated. Necrotic cells (panel B of FIG. 3) were counted on five different tubules per slide at high power (400×) (mean±S.E.M. *=p<0.05 by ANOVA), In FIG. 4 macrophages were counted around 5 different tubules per slide at high magnification (400×) in hematoxyllin-eosin stained sections by a reviewer blinded to treatment and averages±S.E.M. calculated (*=p<0.05 by ANOVA). Further, there was a nearly 3-fold increase in neutrophils in blood smears from cyclosporin A treated rats (FIG. 5). Blood smears were stained with Wright Giemsa stain and differential cell counts were performed (*=p<0.05 by ANOVA).

EXAMPLE 2

Enteral compositions

In the following compositions MM stands for "mineral mixture", SM for "trace element mixture" and VM for "vitamin mixture". The composition of these three mixtures is as follows:

    ______________________________________                                         Ingredients   g/100 g  Ingredients   g/100 g                                   ______________________________________                                         MM                     VM                                                      Maltodextrins 34.40    Maltodextrins 43.44                                     K citrate/phosphate                                                                          34.60    Sodium ascorbate                                                                             35.00                                     Magnesium dicitrate                                                                          8.20     Vitamin E-Ac. 50%                                                                            16.00                                     Calcium chloride                                                                             8.00     Niacinamide   1.55                                      Sodium citrate/chloride                                                                      9.00     Vitamin A-Acetate                                                                            1.20                                      Citric acid   3.50     Ca-D-Panthothenat                                                                            0.98                                      Choline tartrate                                                                             2.30     Vitamin K.sub.1  1%                                                                          0.71                                      SM                     Vitamin B.sub.12  0.1%                                                                       0.30                                      Maltodextrins 47.79    Vitamin D.sub.3                                                                              0.28                                      Molybdenum-yeast                                                                             18.00    Vitamin B.sub.6                                                                              0.20                                      Chromium-yeast                                                                               9.20     Vitamin B.sub.1                                                                              0.17                                      Zinc sulfate  7.00     Vitamin B.sub.2                                                                              0.15                                      Selenium-yeast                                                                               7.00     Folic acid    0.02                                      Ferrum(II) sulfate                                                                           6.92     Biotin        0.01                                      Copper(II) gluconate                                                                         2.24                                                             Manganese(II) sulfate                                                                        1.12                                                             Sodium fluoride                                                                              0.70                                                             Potassium iodide                                                                             0.03                                                             Composition I Comprising Glycine                                               Water         77.40                                                            Maltodextrins 12.28                                                            Na/Ca caseinates                                                                             4.60                                                             Glycine       3.00                                                             Lipids:                                                                        Palm oil      2.33                                                             Sunflower oil 0.26                                                             Emulsifier Nathin E                                                                          0.13                                                                           100.00                                                           Composition II Comprising Glycine                                              Water         77.40                                                            Maltodextrins 10.10                                                            Na/Ca caseinates                                                                             4.60                                                             Glycine       3.00                                                             MM            2.00                                                             SM            0.05                                                             VM            0.10                                                             β-Carotine                                                                              0.03                                                             Lipids:                                                                        Palm oil      2.33                                                             Sunflower oil 0.26                                                             Emulsifier Nathin E                                                                          0.13                                                                           100.00                                                           Composition Comprising Glycine and Arginine                                    Water         77.40                                                            Maltodextrins 8.93                                                             Na/Ca caseinates                                                                             4.60                                                             Glycine       3.00                                                             Arginine      1.17                                                             MM            2.00                                                             SM            0.05                                                             VM            0.10                                                             β-Carotine                                                                              0.03                                                             Lipids:                                                                        Palm oil      2.36                                                             Sunflower oil 0.23                                                             Emulsifier Nathin E                                                                          0.13                                                                           100.00                                                           Composition Comprising Glycine and Fish Oil (ω-3 fatty acids)            Water         77.40                                                            Maltodextrins 10.10                                                            Na/Ca caseinates                                                                             4.60                                                             Glycine       3.00                                                             MM            2.00                                                             SM            0.05                                                             VM            0.10                                                             β-Carotine                                                                              0.03                                                             Lipids:                                                                        Palm oil      1.32                                                             Sunflower oil 0.23                                                             Emulsifier Nathin E                                                                          0.13                                                             Fish Oil EPAX 3000 TG                                                                        1.04                                                                           100.00                                                           Composition Comprising Glycine and RNA                                         Water         77.40                                                            Maltodextrins 9.96                                                             Na/Ca caseinates                                                                             4.60                                                             Glycine       3.00                                                             Yeast extract RNA                                                                            0.14                                                             MM            2.00                                                             SM            0.05                                                             VM            0.10                                                             β-Carotine                                                                              0.03                                                             Palm oil      2.33                                                             Sunflower oil 0.26                                                             Emulsifier Nathin E                                                                          0.13                                                                           100.00                                                           Composition Comprising Glycine, Arginine and Fish Oil (ω-3 fatty         acids)                                                                         Water         77.40                                                            Maltodextrins 8.93                                                             Na/Ca caseinates                                                                             4.60                                                             Glycine       3.00                                                             Arginine      1.17                                                             MM            2.00                                                             SM            0.05                                                             VM            0.10                                                             β-Carotine                                                                              0.03                                                             Lipids:                                                                        Palm oil      1.32                                                             Sunflower oil 0.23                                                             Emulsifier Nathin E                                                                          0.13                                                             Fish Oil EPAX 3000 TG                                                                        1.04                                                                           100.00                                                           Composition Comprising Glycine, Arginine and RNA                               Water         77.40                                                            Maltodextrins 8.79                                                             Na/Ca caseinates                                                                             4.60                                                             Glycine       3.00                                                             Arginine      1.17                                                             Yeast extract RNA                                                                            0.14                                                             MM            2.00                                                             SM            0.05                                                             VM            0.10                                                             β-Carotine                                                                              0.03                                                             Lipids:                                                                        Palm oil      2.33                                                             Sunflower oil 0.26                                                             Emulsifier Nathin E                                                                          0.13                                                                           100.00                                                           Composition Comprising Glycine, RNA and Fish Oil (ω-3 fatty acids)       Water         77.40                                                            Maltodextrins 9.96                                                             Na/Ca caseinates                                                                             4.60                                                             Glycine       3.00                                                             Yeast extract RNA                                                                            0.14                                                             MM            2.00                                                             SM            0.05                                                             VM            0.10                                                             β-Carotine                                                                              0.03                                                             Lipids:                                                                        Palm Oil      1.32                                                             Sunflower oil 0.23                                                             Emulsifier Nathin E                                                                          0.13                                                             Fish Oil EPAX 3000 TG                                                                        1.04                                                                           100.00                                                           Composition Comprising Glycine, Arginine, RNA                                  and Fish Oil (ω-3 fatty acids)                                           Water         77.40                                                            Maltodextrins 8.79                                                             Na/Ca caseinates                                                                             4.60                                                             Glycine       3.00                                                             Arginine      1.17                                                             Yeast extract RNA                                                                            0.14                                                             MM            2.00                                                             SM            0.05                                                             VM            0.10                                                             β-Carotine                                                                              0.03                                                             Lipids:                                                                        Palm oil      1.32                                                             Sunflower oil 0.23                                                             Emulsifier Nathin E                                                                          0.13                                                             Fish Oil EPAX 3000 TG                                                                        1.04                                                                           100.00                                                           ______________________________________                                    

As already set out above fish oil is a natural source for omega-3 PUFAs whereas sunflower oil is a natural source for omega-6 PUFAs. 

What is claimed is:
 1. A method for the prophylactic and/or therapeutic treatment of renal dysfunction induced by cyclosporins or ascomycins comprising enterally administering to a human being, simultaneous with the treatment with a cyclosporin or ascomycin, a medicament or nutritional formulation comprising an amino acid component consisting essentially of glycine and the physiologically acceptable salts thereof in amount effective to inhibit and/or ameliorate the renal dysfunction.
 2. The method of claim 1 wherein the cyclosporins and ascomycins are immunosuppressants.
 3. The method of claim 1 wherein the cyclosporin is cyclosporin A (Ciclosporin) or PSC 833 ([3'-desoxy-3'-oxo-MeBmt]¹ [Val]² -Ciclosporin).
 4. The method of claim 1 wherein the ascomycin is FK-506 or ASM (33-epi-chloro-33-desoxy-ascomycin).
 5. The method of claim 1 wherein said formulation further comprises one or more omega-3 polyunsaturated fatty acids.
 6. The method of claim 1 which comprises simultaneous treatment wherein the medicament or nutritional formulation additionally comprises a cyclosporin or ascomycin.
 7. An enteral medicament or nutritional formulation comprising a therapeutically effective amount of a cyclosporin or ascomycin in combination with an amino acid component consisting essentially of glycine and the physiologically acceptable salts thereof in an amount effective to inhibit and/or ameliorate the renal dysfunction induced by said cyclosporin or ascomycin. 